Commitments and Contingencies - Additional Information (Details) - USD ($)	3 Months Ended		9 Months Ended
	Oct. 31, 2017	Oct. 31, 2016	Oct. 31, 2017	Oct. 31, 2016	Jan. 31, 2017	Aug. 31, 2016	Jul. 31, 2016
Commitments and Contingencies Disclosure [Abstract]
Operating leases, rent expense	$ 2,300,000	$ 1,800,000	$ 6,600,000	$ 5,000,000
Loss Contingencies [Line Items]
Accrual for contingencies	0		0		$ 0
Operating Lease in New York
Loss Contingencies [Line Items]
Letters of credit outstanding						$ 500,000	$ 1,100,000
Operating Lease in Texas
Loss Contingencies [Line Items]
Letters of credit outstanding					$ 400,000
Operating Lease in Australia
Loss Contingencies [Line Items]
Letters of credit outstanding	$ 200,000		$ 200,000